KM
Contactor
An electrically operated switching device commonly used for repeated switching duties.
SLD / Schematic
Functional block · STC
Star-delta transition controller
Functional block · Switchgear
An independently authored application reference. The drawing shows the named function or circuit relationship; use the project legend and selected equipment documentation for its drafting form and connections.
Browse this installation focusIn plain English
What this block does
Coordinates the documented change from starting winding connection to running connection.
A simple example
In a switchroom motor-control panel, a ventilation motor can receive an automatic start request while a local selector and the motor protection determine whether the feeder is available. For this reference, the drawing identifies “Start sequence and timing” at the input and “Star and delta commands” at the output. Transition arrangement must match the actual motor starter.
What the drawings help you do
Start at the named input: Start sequence and timing. Identify its source device or document and the state represented on the drawing. Follow the named output: Star and delta commands. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Input
- Start sequence and timing
- Output
- Star and delta commands
- Application reference
- An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.
Read the source: SEL-710 motor protection and control
Schematic · STC
What it represents
Coordinates the documented change from starting winding connection to running connection. A motor feeder combines switching, motor protection and an operating command. Starting permission, running feedback and protection trip are different signals even where one relay or controller processes all of them.
In a switchroom motor-control panel, a ventilation motor can receive an automatic start request while a local selector and the motor protection determine whether the feeder is available. For this reference, the drawing identifies “Start sequence and timing” at the input and “Star and delta commands” at the output. Transition arrangement must match the actual motor starter.
Link the motor tag to its contactor, protective device and process permissives. The control diagram must identify stop priority, feedback and restart philosophy without supplying unverified settings. The functional block is an independent explanation of this named application. Equipment-specific ratings, terminal connections and operating conditions must be established in the project documentation.
How to read it
- Start at the named input: Start sequence and timing. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Star and delta commands. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Transition arrangement must match the actual motor starter.
- Link the motor tag to its contactor, protective device and process permissives. The control diagram must identify stop priority, feedback and restart philosophy without supplying unverified settings.
Information to show or reference
- Label the source and connection reference for start sequence and timing.
- Identify the destination and defined state of star and delta commands.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Transition arrangement must match the actual motor starter.
A distinction that matters
Transition arrangement must match the actual motor starter. This reference describes the named application; it does not establish a new IEC graphical symbol, an ANSI device-function number or an exact manufacturer connection diagram.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
SEL-710 motor protection and control
Public technical context for motor-feeder control interfaces. Motor feeder thermal, starting and control functions. The application text and educational graphic are independently authored; the publisher does not certify this representation.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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